Eastern South America: Eastern slopes of the central Andes in Peru

The Peruvian yungas are sub-tropical montane deciduous and evergreen forests which flank the eastern slopes and central valleys of the central Andes from northernmost to southernmost Peru. Vegetation is extremely diverse, and in many places forms an elaborate mosaic of habitat types. The terrain in steep and rugged, and altitudes vary dramatically within the ecoregion, from high plains to precipitous valleys. Precipitation ranges from 500-2000mm annually, and deciduous trees occur in dry habitats. Otherwise the region has lush, dense vegetation, high species diversity and richness, as well as a number of endemic species.

Scientific Code

(NT0153)

Ecoregion Category

Neotropical

Size

72,100 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionThis region maintains one of the richest montane forest ecosystems in the Neotropics. Many species of plants, birds, mammals, reptiles, amphibians and invertebrates are found only in this part of the planet.

It is located in the central part of South America exclusively in Peru and occupies an area of 188,735 km2 (Roca, R. 1996). The climate varies from moderately temperate to tropical with heavy rains that can exceed 6000 mm per year and decline between May and August. At altitudes above 2500 m. ASL, average temperatures range from 6-12 ºC (in the northern section) and 8-22 ºC (in the southern section). In low areas, the average temperature is 25 ºC. Most of the ecoregion lies on the sub-Andean strip, a mountainous region running parallel to and at the base of the eastern range. It consists primarily of Mesozoic-Cenozoic sediments. Most of the soils are acid, poorly-developed, and shallow with varied lithology based on sedimentary rocks (eutric and dystric cambisols). Alluvial soils predominate in the landscape (Rodríguez, L. 1996). It has a very complex orography whose determinants include a mountainous surface full of cliffs, ridges, hillsides and valleys, with a steep and highly dissected topography.

It is an area with montane forests with more than 3000 species of flora and more than 200 species of vertebrate fauna. There are at least 200 species of orchids (such as the genera Epidendrum and Maxilaria). Below 3500 meters, there are the so-called cloud forests with the presence of bamboo (Chusquea) and arboreal ferns (Cyathea spp.) (Ferreyra, R. 1988). Below 2700 meters, the forest becomes more rich in species such as cedar, cetico [trumpet-wood] and relatives of papaya (Carica spp). Above 3500 meters, there are scrublands and wet rocky thickets with some shrubs and land orchids as well as forests of romerillo (Podocarpus). (Weberbauer, A. 1945, INRENA, 2000).

Biodiversity FeaturesThis ecoregion has at least four species of endemic birds like the Gallito de las rocas (Rupicola peruviana) and endemic species of butterflies of the genera Dismopha, Callithea, Paridos, Morpho. Notable among mammals are the ratón marsupial (Lestos inca) and the añuje de altura (Dasyprocta kalinowsky), as well as the sachacabra (Pudu mephistopheles) and the armadillo peludo (Dasypus pilosus).

It is also an area with a concentration of species of limited distribution such as the paujil cornudo (Crax unicornis koepckeae), picaflores (Metallura theresiae, Heliangelus rejalis), lechuza (Xenoglaux loweryi) and ranas (Dendrobates mysteriosus). (Pulido, V. 1991, Rodríguez, L. 1996)

Current StatusThe network of protected areas in the ecoregion consists of the following conservation units: Cutervo National Park, Tingo María National Park, Manu National Park (more than 800 species of birds and 200 species of mammals) (INRENA, 2000).

Types and Severity of ThreatsThe ecoregion is in an almost critically endangered state (Roca, R. 1996) due to migratory agriculture, coca, deforestation, selective cutting and gradual urban development.

Justification of Ecoregion DelineationThese forests form the elevational transition zone from high puna and páramo habitats to lowland moist forest habitats along the eastern slopes of the Peruvian Andes. Linework for these ynugas follows the Instituto Geográfico Nacional (1987) classification of "high forests (yungas)" from the Marañon Valley southwards to the Inambari River, near the border with Bolivia. This river was considered to represent a significant distinction between these and yungas extending further south due to floral and faunal distributions and species endemism.